With the weather of the past and the coming period, downy mildew feels completely in its element. Steven Dorrestijn advises to stop the fungus in time with early spraying against this aggressive attacker.
"It has been really moldy weather for a long time," says Steven Dorrestijn. "And downy mildew has already been detected in onion onions. That is why growers must start spraying against the disease as soon as the swelling starts. Because if you wait until you see the fungus, you will be too late. Once downy mildew is in your crop, you will get it usually doesn't come out anymore." However, most onion plots will not have reached that stage yet, the Syngenta advisor estimates.
"Many plots were sown late and of the plots that I visited myself, most are now in the stage of one to three pipes. Anyway, the longest day is now behind us, so the rounding is imminent. But it will happen on many plots will be a little later than the end of June, which we are used to."
Clean crop
According to the Syngenta advisor, there is only one method for an effective approach to downy mildew fungus: "Start on time with a clean crop and then simply maintain a strict weekly schedule. And if a weekly interval does not work, try to spray earlier. The insidious thing about downy mildew is the long incubation period. It can take up to three weeks after an infection before you see the fungus appear. But then you are too late It is difficult to estimate whether infection has occurred. Every year I see growers making the mistake of starting too late when it is warm and dry no more curative remedies."
Also leaf spots
According to Dorrestijn, the choice of means is: Orondis® Plus Amistar® the best choice for spraying T2 and T5. "In addition to downy mildew, the Orondis Plus Amistar also tackles secondary fungi such as leaf spot disease. Growers may think that it is too early for leaf spot disease, but that fungus can already be dormant early in the season. It needs splashing water to spread. necessary and there has been enough of that lately." The Orondis Plus Amistar may be applied a total of three times with a minimum interval of 21 days. In the intervening periods you can then alternate with other substances. Dorrestijn: "That is in any case sensible from the point of view of resistance management. And in any case, we need all available resources in the onions to cover the entire season." The Syngenta employee reminds growers that they may spray a product containing the active substance oxythiopiprolin a maximum of three times. "The advisors usually keep an eye on this, but forewarned counts for two."
An important advantage of Orondis Plus Amistar as an early spray is that it is gentle on the crop. Steven: "You have no phytotoxic reaction and therefore no inhibition. And the product is hard on downy mildew. We also see this in our tests. The good effect of Orondis Plus Amistar is confirmed every year in both spraying schemes and in practice schemes. It is not without reason that it has quickly established itself as a staple in many onion growers' fungicide schedules."